Question: When did Song Young-gil become head of the government of Incheon?
Paraphrase: What date did the head of the government of Incheon change to Song Young-gil?
SPARQL (Wikidata): SELECT ?value WHERE { wd:Q20934 p:P6 ?s . ?s ps:P6 wd:Q484024 . ?s pq:P580 ?value}